paper

Unravelling competing microscopic interactions at a phase boundary: a single crystal study of the metastable antiferromagnetic pyrochlore Yb $_{2}$ Ge $_{2}$ O $_{7}$

arXiv:1912.09448 · doi:10.1103/PhysRevB.102.134418

Abstract

We report inelastic neutron scattering measurements from our newly synthesized single crystals of the structurally metastable antiferromagnetic pyrochlore Yb $_{2}$ Ge $_{2}$ O $_{7}$ . We determine the four symmetry-allowed nearest-neighbor anisotropic exchange parameters via fits to linear spin wave theory supplemented by fits of the high-temperature specific heat. The exchange parameters so-determined are strongly correlated to the values determined for the $g$ -tensor components, as previously observed for the related Yb pyrochlore Yb $_{2}$ Ti $_{2}$ O $_{7}$ . To address this issue, we directly determined the $g$ -tensor from electron paramagnetic resonance of 1% Yb-doped Lu $_{2}$ Ge $_{2}$ O $_{7}$ , thus enabling an unambiguous determination of the exchange parameters. Our results show that Yb $_{2}$ Ge $_{2}$ O $_{7}$ resides extremely close to the classical phase boundary between an antiferromagnetic $I^_{5}$ phase and a splayed ferromagnet phase. By juxtaposing our results with recent ones on Yb $_{2}$ Ti $_{2}$ O $_{7}$ , our work illustrates that the Yb pyrochlore oxides represent ideal systems for studying quantum magnets in close proximity to classical phase boundaries.

Unravelling competing microscopic interactions at a phase boundary: a single crystal study of the metastable antiferromagnetic pyrochlore Yb2​Ge2​O7​

Abstract

Unravelling competing microscopic interactions at a phase boundary: a single crystal study of the metastable antiferromagnetic pyrochlore Yb $_{2}$ Ge $_{2}$ O $_{7}$